It is well known to utilize a slip mechanism for anchoring and/or supporting a downhole well tool in a well conduit such as a casing.
The slip mechanism of a downhole well tool such as a hanger or a packer bites into and locks into the casing. The set slip mechanism supports the weight of a tubing string attached to a hanger or a packer and any pressure differentials to which the packer may be subjected. Setting the well tool requires an axial load from a setting device which is translated into a radial force by means of a wedge which forces the exterior teeth of the slip into the casing interior wall. The weight of the tubing string may then be supported by the slip teeth. Since the magnitude of the radial force translated by the wedge is directly proportional to the magnitude of the axial force, an increased axial load will increase the radial holding force.
In some instances, using conventional slips the weight of the tubing string may be great enough so that the corresponding radial force will overstress the casing. This will not normally occur in a bottom hole packer installation where the packer is set in casing that is surrounded by cement. The support from the cement gives the casing greater load carrying capacity. However, in a hanger or shallow set packer installation, the casing may be unsupported and may be subjected to high tubing pressure due to weight and/or pressure loads. In order not to overstress the casing, hanging loads applied to shallow set hangers or packers must be limited.
The present invention is directed to a slip mechanism for a well tool which distributes the radial load transmitted to the casing wall more evenly and over a larger area thereby allowing longer and heavier tubing loads to be supported without overstressing the casing.